Are Radar Detectors Legal or Illegal in California? (CA State Law)

The simple answer is that Radar detectors are only legal in private vehicles in California. However, the radar detector must not be mounted to the windscreen.

Using a radar detector in a "commercial" vehicle is illegal.

California also have laws that ban radar jammers and laser jammers from any type of vehicle. Simply being in possession of a jammer without an appropriate exemption is illegal and can put you in jail. The law also makes it illegal to buy, possess, manufacture or sell jamming devices. Note: This law only applies to jammers and does not apply to detectors.

When it comes to military bases, radar detectors are also prohibited in any type of vehicle throughout the country (including California).

What is a Commercial Vehicle?

The federal definition of a commercial vehicle includes:

Any vehicle with a gross vehicle weight rating (GVWR) of more than eighteen thousand pounds (Ref: 94-R-0240). This includes private vehicles.

Vehicles that are designed to transport more than 9 or more passengers (including the driver) for compensation

Vehicles designed to transport 16 or more passengers (including the driver) – even if it is not for compensation

California State Law

(a) A commercial vehicle is a motor vehicle of a type required to be registered under this code used or maintained for the transportation of persons for hire, compensation, or profit or designed, used, or maintained primarily for the transportation of property.

(b) Passenger vehicles and house cars that are not used for the transportation of persons for hire, compensation, or profit are not commercial vehicles.

(c) Any vanpool vehicle is not a commercial vehicle.

To properly understand the definition of a commercial vehicle in California, we need to refer to Chapter 13, Section 13.000 of the Vehicle Industry Registration Procedures. The definition is six pages long and includes a few surprises that may catch you out.

First and foremost, the definition does not limit the GVWR to 10,000 lbs or more. The refined definition includes (but is not limited to):

The key point here is that it doesn’t matter if the vehicle is traveling between states (interstate) or staying in its home county or city (intrastate). This definition is designed to address the gap in the federal regulations for commercial vehicles between 10,000 and 18,000 lbs, and to include several additional classes of vehicles with a GVWR of less than 10,000 lbs.

Military Bases

The use of a radar detector on military bases is strictly prohibited throughout the United States.

This is not normally a problem as most bases have a checkpoint before you can enter. The security personnel usually request drivers to unplug and remove radar detectors from windscreens or dashboards before passing through the checkpoint.

If you refuse to remove the radar detector, you will almost certainly be refused entry to the base.

Windscreen Mounting

The other thing you need to think about is how you intend to mount your radar detector.

Even though it may be legal to own and operate a radar detector, almost 70% of states have made it illegal to attach anything to a windscreen that may obstruct the drivers vision. (This includes California)

While some states restrict the rules to devices attached with suction cups, others have rules based on the location of the device (directly in the drivers line of sight) or its overall size and weight.

California has a specific set of regulations related to objects attached to windscreens.

Extracted sections of Section 26708 of the Vehicle Code state:

(a) (1) A person shall not drive any motor vehicle with any object or material placed, displayed, installed, affixed, or applied upon the windshield or side or rear windows.

(b) This section does not apply to any of the following:

(11) An electronic communication device (..text ommited..) if the device provides either of the following:
(A) The capability for enforcement facilities of the Department of the California Highway Patrol to communicate with a vehicle equipped with the device.
(B) The capability for electronic toll and traffic management on public or private roads or facilities.
(12) A portable Global Positioning System (GPS), (..text ommited..) , if the system is used only for door-to-door navigation while the motor vehicle is being operated.

Note : The above text is a partial extract. Please refer to Chapter 4 (Section 26708) of the Vehicle Code for a complete version

In total there are 14 listed exceptions. We have only included an abbreviated version of items 11 and 12 in the sections quoted above.

The important thing is that Radar Detectors are not included in the list and because of this, they are illegal to attach anywhere on the windscreen, side or rear windows.

If you intend to use a radar detector, you need to mount the device on a sun visor or on the dash.

Windscreen mounted radar detectors are especially easy for enforcement officers to spot when they’re looking at your windscreen, so the chances of getting a ticket are quite high!

Radar Jammers

Even though radar "detectors" are legal, radar "jammers" have been highly illegal in all states under federal law since 1996.

FCC Public Notice DA 96-2040 states

Radar Jammers are transmitters tuned to interfere with (“jam”) a radar signal. The intentional use of jammers is considered “malicious interference” and is strictly prohibited by the Communications Act of 1934, as amended, as well as by FCC Rules. Anyone using a jammer risks such penalties as losing an FCC license, paying a fine, or criminal prosecution.

Section 333 of the Communication Act of 1934 states

Willful or malicious interference. No person shall willfully or maliciously interfere with or cause interference to any radio communications of any station licensed or authorized by or under this Act or operated by the United States Government.

Radar jammers or scramblers work by modifying or interfering with the signal that bounces off your vehicle before it returns to the enforcement officer. Some jammers do this by overwhelming the police radar gun and other change the Doppler signal or scatter the signal.

If you are caught with a radar scrambler or jammer, you could end up facing a felony charge and be liable for a large fine and/or jail time. The use of a radar jammer is a federal offense and also violates FCC regulations. The fine for a second offense can be as much as $10,000 and up to two years in prison. Even a first offense is up to a year in jail.

Laser Jammers

Laser jammers (vs laser detectors) are not banned by federal law.

A laser jammer works by detecting the laser light from a police laser gun. It decodes the signal and transmits bursts of invisible light back to the sender. When the light is at the right frequency and pulse rate, it confuses the laser gun and stops it from displaying your speed.

While radar jammers are banned by the FCC because they can cause serious issues for aircraft navigation, police radar equipment, and other radar controlled devices, laser jammers are a lot less disruptive because they only transmit stray beams of light to interfere with the incoming signal.

California Vehicle Code Section 28150 states

(a) No vehicle shall be equipped with any device that is designed for, or is capable of, jamming, scrambling, neutralizing, disabling, or otherwise interfering with radar, laser, or any other electronic device used by a law enforcement agency to measure the speed of moving objects.

There are other sections of this clause that make it illegal to be in possession of a jamming device or to transport them without a federal license carried in the vehicle while they are bing transported.

Nearby States

You should always keep in mind that laws vary from state to state and if you live near a state line or travel interstate the laws may be different from your home area. This means you can easily break the law without realizing it.

This is especially true if you travel through Washinton D.C. or Virginia. These states have a complete ban of radar detectors (even in private vehicles) and they strictly enforce the ban.

References:1. Note that this article is expressing an opinion as to the legality of radar detectors and is not providing legal advice. I am not a lawyer and this is not legal advice. Laws can change over time so please do your own research.